refactor(folio): introduce nested KotlinConf-style modules

Split the monolithic :composeApp into :core, :app:shared,
:app:ui-components, and :app:androidApp. The old module is still
present and remains the source of truth until the next commits remove
it; both compile in parallel to keep iOS/Android builds green during
the cut-over.

Highlights:
- :core - SQLDelight schema + LedgerStore + Repository (now an
  injectable class, not a singleton object). Methods are suspend to
  match generateAsync = true.
- :app:ui-components - design system primitives. IconButton/AppButton
  APIs revised: label = real contentDescription, testTag = stable
  selector. Drops the data-carrier description argument.
- :app:shared - per-screen ViewModels colocated with screens; pure
  composables on (state, onEvent); LocalAppComponent CompositionLocal
  for hand-rolled DI; @Serializable Route. Hosts the iOS framework
  (baseName Shared).
- :app:androidApp - thin Android entry that constructs the
  DriverFactory and hands it to App().
- gradle/libs.versions.toml centralises versions; settings.gradle.kts
  enables type-safe project accessors.

Deferred to follow-up PRs (per the design discussion):
- Metro DI: hand-rolled AppComponent for now; Metro graphs are mostly
  ceremony for an app this size and add KSP/version risk.
- Navigation3: kept the existing Navigator-as-backstack class,
  injected rather than singleton; nav3 isn't shipping a stable
  multiplatform artifact for commonMain consumption yet.
- :app:webApp + OPFS sqlite worker: web persistence is real new
  wiring (custom worker on @sqlite.org/sqlite-wasm). Master's
  WebLedgerStore + Snapshot is being removed by this PR; web stays
  buildable as a klib but no app-level wasm binary lands here.

examples/folio/build.gradle.kts

@@ -1,7 +1,12 @@
 plugins {
-    id("com.android.application") version "8.13.2" apply false
-    id("org.jetbrains.kotlin.multiplatform") version "2.3.20" apply false
-    id("org.jetbrains.kotlin.plugin.compose") version "2.3.20" apply false
-    id("org.jetbrains.compose") version "1.10.3" apply false
-    id("app.cash.sqldelight") version "2.3.2" apply false
+    alias(libs.plugins.android.application) apply false
+    alias(libs.plugins.android.library) apply false
+    alias(libs.plugins.kotlin.multiplatform) apply false
+    alias(libs.plugins.kotlin.android) apply false
+    alias(libs.plugins.kotlin.plugin.compose) apply false
+    alias(libs.plugins.kotlin.plugin.serialization) apply false
+    alias(libs.plugins.compose.multiplatform) apply false
+    alias(libs.plugins.sqldelight) apply false
+    alias(libs.plugins.ksp) apply false
+    alias(libs.plugins.metro) apply false
 }